Hardness tester



M y 14; 1935. R. E. FRmKEY 2,001,097

. I HARDNESS TESTER Filed Oct. 2, 1933 INVENTOR Poya/ f. Frl'cf/eg lit till

antiwar nnnss 'rns'rn RoyalE. Frlckey, San Francisco, @alllt,

to Welding Service, line, San ltranelaco Qalli... a eorporatlonoi tDaliioa appellants carat a late, Smlal Nb. scram 3 @laims.

'lhis invention relates generally to devices for determining the hardness of various metal bodies.

it is an. object of the invention to provide a device of the above character which will be of utmost simplicitmand which can be utilized under field conditions as well as in laboratories or shops. In this connection the invention is characterized by the use of a relatively few numbers of parts which are of rugged construction, and which can be relied upon to give the results desired.

A further object of the invention is to provide a hardness testing device which will have an accuracy comparing favorably or even superior to more complicated prior devices for this purpose.

Further objects of the invention will appear from the following description in which the preferred embodiments of the invention are set forth in detail in conjunction with the accompanying drawi.

Referring to the drawing:

Figure l is a side elevational view, in cross section illustrating a device incorporating the present invention, and showing the manner in which comparative indentations or impressions are made.

Fig. 2 is a view similar to Fig. 1, but showing the device in its normal form.

Fig. 3 is a cross sectional detail taken along the line 3-3 of Fig. 2.

Fig. 4 is a side elevational view, showing a simplied modification of the invention.

Fig. 5 is a cross sectional detail taken along theline 5-5 of Fig. 4.

Referring first to that form of the invention illustrated in Figs. 1 to 3 inclusive; the-deviceconsists of a metal body in the form' of a bar It, which is of known hardness. Retained adjacent one side of this bar there is an impression member ii in the form of a metal ball which should be of greater hardness than eitheir421 i:- an ill or the body to be tested. To serve 'as ineiims for retainv ing the ball ii in its desired position, and also to. facilitate handling of the, device, the: bjar'ls, shown slidably disposed within a metalsl'eeve l2. sleeve is provided with. an aperture 03 so thatthe ball it may directly contact one face of the, bar. Surrounding one end portion of the sleeve it there is a body it of suitable resilient material. such as soft vulcanized rubber. The lower sidej of bodyv f 'thetested, is provided withan it, which is intended to contact oneface'; wor or body to be (oi. tablt) aperture are distorted to form an edective trictional engagement.

In order to facilitate the imparting oi a proper impact or blow to the bar it, without scarring the same, I have shown a metal head. it fixed wit the. upper portion of body it. The depending portion it of head ii is normally slightly out of contact with the upper side of bar it, but may be forced downwardly into contact with the bar, theaperture it in sleeve it. 7

In order to locate bar it in definitely is positions in taking successive impressions, deten means somewhat as illustrated can be employed.

Thus, slidably disposed within sleeve it there is lower face of resilient body it with the "upper surface of the rail, with the axis of the bar it extending substantially parallel to the suri'ace being tested. The head ll is now struck a blow with a hammer or like tool, thus causing this head in turn to force bar it downwardly against ball ii, whereby the ball is caused to indent or form an impression in both the underside of the bar iii and the surface of the radii. The operator now inspects the indentation formed in the bar in d compares it with the indentation formed in the body 216. By the aid of a microscope or magnifying glass, the diameters of these indentations can be accurately determined.

Knowing-the hardness of the bar. it; it is possible fromthisdata to determine the hardness of the surface of body 2%, with fair accuracy. In this connection the data secured can be translated into terms of hardness by referring to suitable calibration eurves, or can be determined by computationas follows:

Assuming that the test bar has a hardness oi dilO Brinell, that's represents the dieter of the impressionin' the test bar and y represents the diameter of the impression in the body being tested; then'the hardness of the body can be oleerniinedgby the following equation:--

all

arias-sixes the test bar impression is as w I proper impression at all times.

rial. Body 28 is provided with an aperture 29 within which the hard metal ball II is retained.

' This simplified device is utilized in the same manner as the modification of Figs. 1 to 3 inclusive, except that the blow from a hammer or like tool is applied directly to the upper side of the bar 21. In making successive impressions the body 28 is moved to different spaced positions along the bar 21.

It is characteristic of my device that in making an impression, substantially no movement is imparted to ball I I, but this ball is caused to simul taneously indent both the bar of known hardness, and the surface of the body being tested. Provided a single blow is applied with a hammer or like tool, the ball is instantaneously'driven into both the test bar and the surface of the body being tested, and is then immediately retracted, due to expansion of the rubber which is compressed during the interval that the blow is applied. The rubber surface which contacts the surface being treated prevents lateralskidding at the time a blow is struck, thus insuring a Assuming that the operator uses the device with a fair degree of intelligence, and applies a hammer blow. of reasonable momentum in taking successive readings, a high degree of accuracy will be aflorded.

I claim:

1. In a hardness testing device, a metal member of known hardness, an impression ball substantially harder than said member and adapted to be interposed between one side oi! said member and the body to be tested, whereby an impact upon said member causes the ball to simultaneously indent both said member and said,body, and means forming a yieldable work-engaging friction surface surrounding the ball, said surface being spaced from the bar a distance greater than the diameter of the ball.

2. In a hardness testing device, a metal bar of known hardness, an impression ball formed of metal substantially harder than the metal of said bar and adapted to be interposed between one side 0! said bar and the body to be tested, whereby an impact upon said bar causes said ball to indent both the bar and said body simultaneously, and means including a body of resilient vulcanized rubber for retaining said ball adjacent one side of said bar and for forming a work engaging friction surface.

3. In a hardness testing device, a metal bar of known hardness, an impression ball formed of metal substantially harder than the metal of said bar and'adapted to be interposed between one side of said bar and the body to be tested whereby an impact upon said bar causes said ball to indent both the bar and said body simultaneously, and a body of resilient vulcanized rubber surrounding the ball at one side of the bar,'

said last body forming a friction surface for engaging with the body to be tested, the friction surface being spaced from the bar a distance greater than the diameter of the ball.

ROYAL E. FRICKEY. 

